118 Messrs. K. Honda, T. Terada, and D. Isitani on th 
te 
same as those o£ the ordinary secondary undulations. In this 
connexion we quote a few of the most accurate records from 
modern occurrences. 
On June 15, 1896, the most destructive and disastrous 
sea-wave of modern times visited the coasts of Sanriku in 
Japan. It originated in the sea about 150 km. off the coast 
of Sanriku, the product of a submarine earthquake, and soon 
assumed such proportions that at Yoshihama the height re- 
corded was 24 m. It swept away many towns and villages 
along the coast of Sanriku covering a distance of about 320 km.. 
In all 22,000 lives were sacrificed. The sea-wave also crossed 
the Pacific, reaching the western coast of America. It 
left its records on the tide-gauges of Honolulu and 
San Francisco. 
In the following table the observed periods, together with 
those observable in ordinary cases, are given. 
Station. 
Sea -Wave. 
Ordinary Undulation. 
Hanasaki 
Hakodate 
Miyako 
Ayukawa 
7 m 
23 m 6 , 47 m -3— 52 m "l 
8, 16 
7-8 
7 
15 
26-0—234 
62, 34-3 
(Coast) 
21 m *9— 24 m '5 ; 45 m '5— 57 m, 5 
12; 213—22 
6-8-8-9 
(Coast) 
13-8—156 
Choshi 
Moroiso 
Honolulu 
San Francisco ... 
Now, according to the results of our investigation, the 
periods of the principal sea-waves on the coast of Sanriku are 
7 m -8 m and 15 m -17 m . The records of two coast-stations, 
Hanasaki in Hokkaido and Choshi in Shimosa, though they 
lie on opposite sides of Sanriku and are a considerable 
distance from each other, showed the existence of the same 
wave. At Miyako. which is the nearest station at which the 
sea-wave was scientifically observed, the periods of the wave 
were different from those in ordinary cases. Though actual 
observations are wanting, the same remark seems to apply to 
the places where the sea-wave produced its most disastrous 
effect. In distant bays, Hakodate and Moroiso, the periods 
of the wave are the same . as those usually observed. The 
periods observed at Honolulu and San Francisco are also 
the same as those observable in the case of other sea-waves. 
On February 1, 1906, in our time, a strong earthquake was 
